1dxo

CRYSTAL STRUCTURE OF HUMAN NAD[P]H-QUINONE OXIDOREDUCTASE CO WITH 2,3,5,6,TETRAMETHYL-P-BENZOQUINONE (DUROQUINONE) AT 2.5 ANGSTROM RESOLUTION
(see also NADH quinone oxidoreductase (NQO1) with inhibitor dicoumarol)



Superposition of the active site of dicoumarol/hNQO1 complex (residues important for ligand interactions are in stick representation and colored magenta, 2f1o) with the apo hNQO1 (1d4a, residues important for ligand interactions are colored blue ). Dicoumarol is colored in cyan ; FAD is colored in orange. The RMSD between the apo hNQO1 (1d4a) and hNQO1 in complex with dicoumarol is 0.36Å for the 546 Cα atoms. The dicoumarol-hNQO1 binding causes several structural changes. The most prominent of them is Tyr 128 and Phe 232 movement in the first monomer. These residues are located on the surface of the NQO1 catalytic pocket. The distance between these residues increases from ~5 Å in the apo hNQO1 to ~12 Å in the dicoumarol/hNQO1 complex. Quinones (including duroquinone (2,3,5,6-tetramethyl-p-benzoquinone) are substrates of NQO1 (it catalyzes two-electron reduction of them to hydroquinones). Duroquinone (yellow) binds to the active site by interactions involving the FAD and several hydrophobic and hydrophilic residues in the duroquinone-NQO1 complex (1dxo). The structure of the hNQO1 dimer in complex with duroquinone is also similar to that of hNQO1 in complex with dicoumarol (RMSD is 0.33Å for the 546 Cα atoms). In this case, the main differences between these two structures, as well as to that of apo hNQO1, involve the distance between residues Tyr 128 and Phe 232 of the first monomer. The FAD molecule has very similar conformation in both hNQO1-duroquinone (pink) and hNQO1−dicoumarol (orange) complexes.

About this Structure
1DXO is a 4 chains structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.